Deep Vein Thrombosis
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Definition Aetiology Pathophysiology Risk factor Sign and Symptoms Investigations Management
Definition
Venous thrombosis, also known as deep vein thrombosis (DVT), is a condition where a blood clot is formed in one of the body's deep veins, typically in the leg. However, it can also occur in the pelvis, arm, and other deep veins. The blood clot may partially or completely obstruct blood flow in the affected vein, resulting in localised swelling, pain, and redness. If a blood clot fragment breaks off and travels through the bloodstream, it can cause pulmonary embolism (PE), a potentially fatal condition.
Aetiology
The main cause is immobility, which often happens after prolonged bed rest or after surgery.
Other causes:
Increased age
cancer (know or unknown)
Hormone therapy
Genetic conditions
Obesity
Smoking
pregnancy
Trauma
Pathophysiology
The formation of blood clot occur in a deep vein of the body (usually lower limbs)
This occurs because there is a disruption in the normal flow of blood
Disruption causes a buildup of platelets, fibrin, blood cells within the vein leading to a blood clot formation
A small clot generally does not cause any symptoms. However, if the clot is big enough and/or it is a vital area of the body it can lead to swelling, pain, tenderness.
If the clot dislodge and travels to the lung it can cause a pulmonary embolism (PE).
Risk factors
Immobility
Surgery
Trauma
Cancer
Pregnancy
Male sex
Smoking
Varicose veins
Hormone therapy
Sign and symptoms
Unilateral, throbbing, localised pain that occurs when walking or bearing weight, as well as calf swelling (or more rarely, swelling of the entire leg).
Tenderness around calf area.
Changes to the skin, including oedema, redness, and warmth.
Vein distension.
Shortness of breath,
chest pain
coughing.
May have increased heart rate.
O/E chest you may hear pleural rub (described as sandpaper rubbing against itself). This may indicate pulmonary embolism (PE).
Investigations
Examine the leg and thigh for swelling by measuring the leg's circumference 10 cm below the tibial tuberosity and comparing it to the asymptomatic leg. A difference of more than 3 centimetres between the extremities increases the risk of developing a deep vein thrombosis (DVT).
Assess the affected side for edoema and dilated collateral superficial veins.
Utilise the DVT Wells score to determine the likelihood of DVT and guide subsequent management (see table 1).
Blood test - D-dimer
Ultrasound doppler
Table 1, DVT Wells score table:
| Clinical Feature | Points |
|---|---|
| Active cancer | 1 |
| Paralysis, paresis, or immobilization of lower extremity | 1 |
| Recently bedridden for more than 3 days, or major surgery within the past 12 weeks | 1 |
| Localized tenderness along the distribution of the deep venous system | 1 |
| Entire leg swelling | 1 |
| Calf swelling at least 3 cm larger than asymptomatic side (measured 10 cm below tibial tuberosity) | 1 |
| Pitting edema confined to symptomatic leg | 1 |
| Collateral non-varicose veins | 1 |
| Previously diagnosed DVT or PE | 1 |
Interpretation:
A score of 0 or less: low probability of DVT
A score of 1-2: moderate probability of DVT
A score of 3 or more: high probability of DVT
Management
If suspected DVT refer to local DVT clinic
Otherwise treatment options are the following:
Anticoagulation medication: such as low molecular weight heparin or oral medications such as warfarin or direct oral anticoagulants (DOACs) such as apixaban or Rivaroxaban.
Thrombolysis to dissolve the clots such as Streptokinase
Compression stockings to improve flow
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